How to use ImportC to import WebGPU header

[JN]

I would like to use ImportC to automatically import a C header 
into my D project. I've been using Dstep so far which works ok, 
but requires some manual fixes to get the resulting D file to 
compare and it doesn't let me to just drop the C header file.

I created a fresh dub project to try. I try to import this header 
https://github.com/webgpu-native/webgpu-headers/blob/main/webgpu.h . I put webgpu.h file next to app.d.

My code is:

```
import std.stdio;
import webgpu;

void main()
{
}
```

it builds.

Then I tried to output one of the enums to see if it works:

```
import std.stdio;
import webgpu;

void main()
{
	writeln(WGPUBlendFactor_Dst);
}
```

and it says:

     Starting Performing "debug" build using 
C:\D\dmd2\windows\bin64\dmd.exe for x86_64.
     Building test_importd ~master: building configuration 
[application]
     source\app.d(6,10): Error: undefined identifier 
`WGPUBlendFactor_Dst`
     Error C:\D\dmd2\windows\bin64\dmd.exe failed with exit code 1.

I tried to do the other commandline but I get this error instead:

     C:\Users\haxx\Desktop\dev\test_importd\source>dmd -c webgpu.c 
-Hf=webgpu.di
     
C:\D\dmd2\windows\bin64\..\..\src\druntime\import\importc.h(134): 
fatal error C1034:
     sal.h: no include path set
     Error: C preprocess command C:\Program Files (x86)\Microsoft 
Visual
     
Studio\2019\Community\VC\Tools\MSVC\14.29.30133\bin\HostX64\x64\cl.exe failed for file
     webgpu.c, exit status 2